There are in the prior art webbing retractors equipped with a pretensioner mechanism and a sensor lock mechanism. The pretensioner mechanism takes-up a webbing by being operated at the time of an emergency of a vehicle. At the time when the sensor lock mechanism senses that the pull-out acceleration of the webbing has become greater than or equal to a predetermined acceleration, the sensor lock mechanism is operated and locks the pulling-out of the webbing.
In this webbing retractor, after operation (after the conclusion of operation) of the pretensioner mechanism, pulling-out of the webbing is impeded due to the sensor lock mechanism being operated.
However, the sensor lock mechanism is operated at the time when the sensor lock mechanism senses that the pull-out acceleration of the webbing has become greater than or equal to the predetermined acceleration. Therefore, the webbing is pulled-out from after the operation of the pretensioner mechanism until the operation of the sensor lock mechanism.